9 facts about cheating that couples -- and singles -- should know

It’s a lot of couples’ worst nightmare: Someone succumbs to temptation and strays.

Maybe it’s an emotional affair — they fall in love with a coworker — or maybe it’s a sexual affair — a one-night stand after a few drinks.

Psychologists have spent years studying the science of infidelity, including what makes someone inclined to cheat, how your partner is likely to react after you cheat, and how to bounce back from cheating.

Below, we’ve rounded up some recent findings and how they might help you maintain a strong relationship.

Men and women react differently to flirting outside their relationship

A 2008 study found that, after flirting with an attractive person of the opposite sex, men were less tolerant of their partner's transgressions -- while women were more so.

It's possible that men don't feel threatened by temptation and women do, or that men do feel threatened but their response isn't to protect the relationship.

The 2008 study also found that men could be taught to use 'if-then' strategies to protect their relationship from tempting alternatives.

In other words: 'When an attractive woman approaches me, I will do (whatever) to protect my relationship.' In fact, after developing their if-then strategy, men were just as likely as women to protect their partnership, as measured through a virtual-reality game.

If you're economically dependent on your spouse, you're more likely to cheat on them

Interestingly, when women are the breadwinners, they're less likely to cheat. When men are the breadwinners -- specifically, when they earn more than 70% of the total household income -- they're more likely to cheat.

We think everyone is cheating -- except our partner

Relationships are bound to disintegrate -- but not yours, of course!

In a recent study, university students reported that the average person of the opposite sex has about a 42% chance of cheating on their partner.

But when it came to their own partners, participants estimated that there was about a 5% chance that their partner had already cheated on them and about an 8% chance that they would cheat on them in the future.

As it turns out, 9% of participants said they'd really strayed.

We feel differently based on the sex of the person our partner cheats with

For a 2015 study, men and women read about hypothetical scenarios in which their partner had sex with someone of a different sex or the same sex.

When researchers asked participants how they would feel about it, they learned that men are more likely to be angry and more inclined to end the relationship when their partner cheats with someone of a different sex. But they're more likely to be aroused when their partner cheats with someone of the same sex.

Women also said they'd feel more negatively if their partner cheated with someone of a different sex. But they'd be more inclined to end the relationship if their partner cheated with someone of the same sex.

Straight men are more distressed by sexual infidelity; straight women are more distressed by emotional infidelity

2013 research found that most heterosexual men say they'd be more upset if their partner was having a sexual relationship with someone else but hadn't fallen in love with that person.

Most women, on the other hand, say they'd be more upset if their partner had fallen in love with someone else but hadn't had sex with that person.

Men are more likely to cheat when they have a milestone birthday coming up

Researchers recently looked at activity on Ashley Madison, a dating site for people who are already in relationships, and came to a fascinating conclusion: Men are more likely to seek extramarital affairs when their age ends in the number nine.

In other words, right before you hit the big 4-0 or 5-0, for example, you have a greater chance of trying to find meaning in life by having a relationship with someone who isn't your partner.

Your genes may influence how likely you are to stray

For example, one study found that infidelity was more common among people who had specific types of oxytocin and vasopressin receptor genes. As Richard Friedman, a professor of clinical psychiatry at Weill Cornell Medical College, explained in The New York Times, vasopressin is a hormone related to social behaviours including trust, empathy, and sexual bonding.

According to the results of that study, a whopping 40% of infidelity in women and 63% of infidelity in men had to do with genetics.

Women are now just as likely to cheat as men are

New York Magazine recently reported that, while infidelity was once men's domain, it's now about equally likely among men and women.

For example, a 2011 study found that about 23% of men and 19% of women in heterosexual relationships reported having cheated on their partner.